At CeBIT AMD organised a demo of its forthcoming APU, Llano. To recap, it will include an Athlon II X4 and a GPU derived from Redwood, which equips the Radeon HD 5600s. Note that AMD has confirmed that this GPU will be equipped with a full UVD3 graphics engine, which will therefore support acceleration of Blu-ray 3D playback, in contrast to AMD’s C and E APUs.

AMD used two laptops for its demo. The first was equipped with a Llano prototype, the AMD A8-3510MX, which corresponds to a quad core version clocked at 1.8 GHz and equipped with a Radeon HD 6620M GPU clocked at 450 MHz (this clock may be slightly different on the final model). The second was based around a Core i7-2630QM clocked at 2 GHz (2.9 GHz in turbo) and equipped with an HD 3000 graphics core clocked at 650 MHz (1.1 GHz in turbo). It has a TDP of 45W and AMD said that this was the same for its Llano prototype. Note that AMD seems to be imitating the Intel mobile CPU nomenclature, by using larger figures.

AMD was of course looking to avoid a straight fight in terms of CPU performance, a fight which the Core i7 would clearly have won. AMD therefore accentuated a usage scenario. First of all a game was launched (benchmark Final Fantasy XIV) and was then left running in the background while a CPU load (Excel script), the playback of an HD video and an OpenGL rendering (SPEC Viewperf) were launched one after the other. While no precise performance figure was given, you can see that performance during processing of the Excel script was similar on both machines, while the 3D renderings were fluid on Llano and very jumpy on the Core i7. More importantly, the Llano machine remained very responsive, in contrast to the Core i7 one which was apparently pushed beyond its limits.

How best to interpret these results? We see several factors as coming into play: a) the Intel drivers are far from being effective in OpenGL and more generally when several graphics applications are running at the same time, b) loading the CPU and GPU in this way means that the Core i7 doesn’t benefit from Turbo and c) Sandy Bridge graphics performance can be significantly affected during high CPU use, as we observed in our report on this. On the Core i7, the last level cache and communication bus are shared between the CPU and GPU cores, whereas in Llano, the CPU and GPU are only linked by the memory controller. The scenario chosen by AMD was therefore very probably chosen to show Llano off in its best light and it’s therefore impossible to draw any general conclusions from the AMD demo.

Llano on the left, Sandy Bridge on the right.

AMD also set up monitoring for total laptop energy consumption, saying that they did everything they could to avoid any differences external to the platform (SSD and identical memory). The screen, though similar, may however have impacted on the results. That said, overall, energy consumption levels were similar, with a slight advantage to the Llano. This advantage became much more significant when SPEC Viewperf was launched: we observed 56W for the AMD solution against 77W for the Intel.

In the guise of a pure graphics test, AMD launched Furmark, which gave Llano a clear advantage. Although the energy consumption display was deactivated during this test, we were able to see, on the wattmetres behind the laptops, that this time the Llano consumed a lot more power: 52W against 37W for the Core i7. Obviously AMD didn’t care to dwell on this, but the score makes sense given their integration of a much more powerful GPU, which is after all the strong suit on this APU. The good news here is that AMD seems to have been able to attach sufficient CPU perforamnce to this GPU within a thermal envelope that is comparable to that of Sandy Bridge.

Of course, this demo leaves us wanting more because, in fact, all it does is confirm what we know already: the Llano GPU is a good deal faster than the Sandy Bridge one. All this still has to be confirmed during real practical examples, as, after all, nobody will be doing their gaming while watching a film and carrying out 3D modelling at the same time!